1. Field of the Invention
This invention relates to a silver halide photographic light-sensitive material and more particularly, to a silver halide photographic light-sensitive material which has improved processing properties and surface characteristics.
2. Description of the Prior Art
In photographic light-sensitive materials, natural hydrophilic high molecular weight materials such as gelatin and/or synthetic hydrophilic high molecular weight materials are usually contained in a silver halide emulsion layer, photographic auxiliary layers such as an intermediate layer, a protective layer and an antihalation layer, and a subbing layer interposed between the above layers and a support. Photographic light-sensitive materials containing hydrophilic high molecular weight materials are usually processed, to form photographic images after exposure with various aqueous solutions having different pH's and salt concentrations at different temperatures for development, stopping, fixing, washing and the like (bleaching is also conducted for color light-sensitive materials).
However, when the photographic light-sensitive material is processed at a higher temperature as in rapid processing, i.e., the procedures used to form images through rapid development and other photographic processings, or when processing requires a long time since the processing includes many steps for various purposes as in the processing of color reversal photographic materials, many disadvantages occur. For example, the photographic light-sensitive emulsion layers and other layers swell excessively and soften, thus with the physical strength being reduced and often resulting in the occurrence of a reticulate pattern, which is referred to as reticulation, on the surface thereof.
These phenomena are undesirable since they markedly decrease the commercial value of photographic light-sensitive materials both for black-and-white photography and for color photography. In recent years, methods for processing a photographic light-sensitive material have become varied, and, as a result, a shortening of the time required for each processing step and thus an improvement in the rate of conducting the photographic processing steps by processing at higher temperatures such as 30.degree. C., 38.degree. C. or 50.degree. C., and not at conventional temperatures near room temperature such as 20.degree. C. or 24.degree. C., have been desired.
As one of the techniques which can be used to satisfy these requirements, incorporation of a large amount of a hardening agent, such as several times to about twenty times the conventional amount, in a photographic light-sensitive emulsion layer or a protective layer in preparing a photographic light-sensitive material, thus imparting, to the photographic light-sensitive material, physical strength to withstand severe processing conditions has previously been considered. However, although this method prevents the occurrence of reticulation to some extent, a substantially complete prevention is not achieved and, in addition, a phenomenon known as "after-hardening", in which the physical strength of an emulsion film gradually changes during the storage of the photographic light-sensitive material, tends to occur, so that maintenance of photographic qualities is difficult. Moreover, this method has the disadvantage that the penetration and diffusion of a developer are hindered in development processing because the degree of hardening of the photographic layers is too high and, thus, sensitivity is substantially reduced.
Other techniques involve subjecting a photographic light-sensitive material after exposure to processing with a bath of an aqueous solution containing a hardening agent, which is referred to as a prehardening bath, immediately before development, or to carry out development and hardening at the same time using a developer also containing a hardening agent. However, these methods have the defects that undesirable results such as fog, a deterioration of other photographic properties, or color contamination, particularly, in color light-sensitive materials, are obtained in using certain types of hardening agents, and that in order to provide photographic layers having the required physical strength within a short processing time without deteriorating the photographic properties, the kind of a hardening agent, as well as the kind of a light-sensitive material applicable, and processing conditions are narrowly restricted. In particular, the method involving processing with a prehardening bath is not a very good technique to use in shortening the photographic processing time and simplifying the processing steps because the number of processing steps is increased.
As another reported method of controlling the occurrence of reticulation, carboxymethylated casein or ethyl cellulose sulfate sodium salt, in place of a gelatin protective layer, is previously coated as an uppermost layer on the emulsion layer side of a photographic light-sensitive material (e.g., as described in U.S. Defensive Publication T887,012). This method is considered to be advantageous in that it is not necessary to incorporate a large amount of a hardening agent in a photographic layer. However, carboxymethylated casein is disadvantageous in that removal therefrom of impurities which have an undesirable effect on photographic properties is difficult, and also, from the viewpoint of the preparation of a photographic light-sensitive material, that it is difficult to form a uniform coated layer on an emulsion layer using an aqueous solution of carboxymethylated casein. On the other hand, ethyl cellulose sulfate sodium salt having good solubility in water is difficult to produce with satisfactory reproducibility. Further, ethyl cellulose sulfate sodium salt also has the defects, for example, that the material has poor long-term storage stability, as might be supposed from the chemical structure of sulfate esters, and also the material is not settable, which is the ability to solidify on cooling after coating, and has poor coating properties. Therefore, ethyl cellulose sulfate sodium salt is not always suitable as a component for use in the preparation of a photographic light-sensitive material.
Silver halide photographic materials usually have a surface layer containing a hydrophilic colloid, of which gelatin is representative, as a binder. Therefore, under high temperature and high humidity conditions the surface of the photographic materials has increased adhesiveness or tackiness and, thus, the photographic materials easily adhere to other materials on contact therewith. This adhesion happens between photographic materials or between the photographic material and another object which contacts the photographic material during the preparation of the photographic materials, photographing, processing, projection and storage, which often causes various problems.
A method which overcomes the above-described problem and is well known to those skilled in the art involves incorporation of an inorganic material such as silicon dioxide, magnesium oxide, titanium dioxide or calcium carbonate, or finely divided particles of an organic material such as polymethyl methacrylate or cellulose acetate propionate in a surface layer, thereby coarsening the surface layer, that is, forming a so-called matted surface, and thus decreasing the adhesiveness. However, such a method is, in practice, disadvantageous in that the following undesirable secondary effects arise: a uniform coated layer can not be obtained since aggregates are formed in a coating solution containing the above-described material; the photographic material tends to be damaged because of the poor smoothness of the material; the movement of a film in a camera or projector is more difficult; the transparency of the images formed is decreased; the graininess of the images formed is impaired; or the like. Accordingly, development of a method for improving the adhesion resistance of a photographic material without the above undesirable secondary effects has been required.
As was described above, reticulation and adhesion are very important problems in the photographic industry, but is is difficult to solve these two problems at the same time using conventional techniques.